L. The unsubmerged portion =

Cubic ft.Ton.Tons.
30 ft. × 5 ft. × 1 ft. =150 ×0·056= 8·40

The submerged portion =

30 ft. × 20 ft. × 1 ft. = 600 × (0·056 – 0·028) = 16·80
25·20

25·20
Consequently the pressure == 0·84 ton per square foot,
30
K

a difference of 0·56 ton per square foot, or 40 per cent. less load.

M. And upon the base of the central portion—

AT LOW WATER.
Cubic ft.Ton.Tons.
30 ft. × 30 ft. × 1 ft. =900 ×0·056= 50·40.
50·40
The pressure is, therefore, equal to
= 1·68 ton per square foot.
30
K
AT HIGH WATER.

N. The unsubmerged portion =